TOPIC:

procedure showOffset;
var
  val: Integer;
begin
  val:= GetLocalTimeOffset; // or any other with options
  ShowMessage(val.ToString);
end;

ShowMessage(DateTimeToStr(Now));

ShowMessage(DateTimeToStr(NowUTC));

procedure TForm1.FormCreate(Sender: TObject);
var
  s: string;
begin
  s:= DateTimeToStr(Now)+' UTC:'+DateTimeToStr(NowUTC)+#13#10;
  ReReadLocalTime;
  s+= (' ReReading:'+#13#10+DateTimeToStr(Now)+' UTC:'+DateTimeToStr(NowUTC));
  Label1.Caption:= s;
end;

procedure TForm1.FormCreate(Sender: TObject);
var
  s: string;
begin
  s:= DateTimeToStr(Now)+' UTC:'+DateTimeToStr(LocalTimeToUniversal(Now));
  Label1.Caption:= s;
end;

program Project1;

uses Windows, SysUtils, DateUtils;

// include winapi methods
function TzSpecificLocalTimeToSystemTime(lpTimeZoneInformation: PTimeZoneInformation; var lpLocalTime, lpUniversalTime: TSystemTime): BOOL; stdcall; external kernel32 name 'TzSpecificLocalTimeToSystemTime';
function SystemTimeToTzSpecificLocalTime(lpTimeZoneInformation: PTimeZoneInformation; var lpUniversalTime, lpLocalTime: TSystemTime): BOOL; stdcall; external kernel32 name 'SystemTimeToTzSpecificLocalTime';

// convert local time to UTC
function DateTimeToUTC(const Local: TDateTime): TDateTime;
var
  TZI: TTimeZoneInformation;
  LocalTime,
  UniversalTime: TSystemTime;
begin
  GetTimeZoneInformation(TZI);
  DateTimeToSystemTime(Local, LocalTime);
  TzSpecificLocalTimeToSystemTime(@TZI, LocalTime, UniversalTime);
  Result := SystemTimeToDateTime(UniversalTime);
end;

// convert UTC to local time
function UTCToLocalDateTime(const UTC: TDateTime): TDateTime;
var
  TZI: TTimeZoneInformation;
  LocalTime,
  UniversalTime: TSystemTime;
begin
  GetTimeZoneInformation(TZI);
  DateTimeToSystemTime(UTC, UniversalTime);
  SystemTimeToTzSpecificLocalTime(@TZI, UniversalTime, LocalTime);
  Result := SystemTimeToDateTime(LocalTime);
end;

// example usage
var
  Local,
  UTC: TDateTime;
begin
  Local := Now;
  UTC := DateTimeToUTC(Local);
  WriteLn('Local:  ' + DateTimeToStr(Local));
  WriteLn('UTC:    ' + DateTimeToStr(UTC));
  WriteLn('Offset: ' + IntToStr(SecondsBetween(Local, UTC) div 60 div 60));
  ReadLn;
end.